World War Z VFX: How to Build a Zombie Apocalypse

By 3DTotal

World War Z VFX Supervisor for MPC, Jessica Norman, reveals how to create virtual armies of zombies, plane crashes and transform one city into another.

Introduction

It's a busy Thursday morning at The Moving Picture Company where the company's London office has just turned in their final shots for World War Z, the post-apocalyptic epic starring Brad Pitt as a former UN investigator tracking down the source of a zombie pandemic.

With MPC's work on the film finally finished, visual effects supervisor Jessica Norman sat down to talk about the company's high-profile contribution, a large part of which involved extensive use of Alice, their in-house crowd system, to create entire armies of fast-moving zombies. "I've been on this show for two years," Norman relates, "so it's a bit sad after working with your little team for such a long time."

Building a Better Zombie

Much of the film's initial VFX shot list was initially divided between MPC and Cinesite, with two different tracks of design work done by Framestore and Legacy FX. As Norman recalls, "The split about which sequences went to which house was handled by the client, but one thing we did share was some of the zombie assets, with MPC doing the large build, for which we obviously built a lot of different characters.

"We had four different body types to deal with, and then we had to make a huge wardrobe of different clothing that could be mixed and matched. We would then send our human and zombie builds to Cinesite at various stages, and I believe we also built some of their costumes for the Philadelphia scenes. Apart from that, we really weren't working on the same sequences.

"Basically when people first turn into zombies, they are not as affected by disease, and I think the scenes that Cinesite were working on were just the first zombie stages, whereas we were working on stages one through three."

The bulk of MPC's early work took place for the Malta shoot, which doubled for Israel during scenes where armies of zombies form swarming human pyramids in order to scale the city walls and attack the panicked residents.

"We had to create a mix of stage one to three zombies all the way through the sequences," Norman explains, "so you might see different stages in the crowd, and depending on how close-up a shot would be, maybe the zombies would be stage three to get more readability on them, as well as to see the difference between zombies and humans. We also had to dirty down the zombie clothing, adding rips and holes to it, which worked better if they were all stage three."

"We had a photo booth set up in Malta, where we took scans of those characters, so we were able to build our characters based on what the makeups looked like"

A big challenge for the MPC team was the fact that their virtual zombies had to integrate seamlessly with the live-action zombie actors. "We had some excellent makeup and prosthetic work in Malta," recalls Norman, "as well as a number of performance artists who were trained in zombie 'body language,' and we used some of those characters as part of our motion-capture work in order to capture the essence of those performances in our CG characters. We had a photo booth set up in Malta, where we took scans of those characters, so we were able to build our characters based on what the makeups looked like.

"There were also shots where a digi-double takes over for an actor, when we had guys jumping over roofs and things like that, and there were a few cases where we did some CG enhancement on zombies, adjusting their heads or contorting their arms or legs. In the story, they come over the wall and land, so we did some augmentation to make it a little more brutal without being too in-your-face."

One of the biggest innovations in terms of zombie movement was the idea that the infected creatures would cluster together in fast-moving groups, even climbing over each other, ant-like, to reach their quarry.

"Some of those pyramids had 5,000 zombies in them"

"During pre-production," Norman remembers, "there was a lot of discussion about how they moved, how they ran, and how they would do anything - even climbing on top of each other - to get to their target. And then we talked about how that would look on a bigger scale. We started looking at patterns in things like schools of fish, or how these dense crowds would run down narrow alleyways and how the zombies with more energy would reach the front only to be taken down by the guys behind them.